I recently started to notice that once my van is.

I need to clarify and add that I only notice this once I have come to a complete stop and then start to accelerate up until I get upto and around 30 mph and then it runs like a top.

I have had 2 problems over the years that may come close to yours. Is the check engine light is on?

1. The torque converter lockup solenoid is defective causing it to remain stuck locked. When you stop
in this condition it would start bucking like a bronco and you then need to throw it into neutral to avoid stalling.
Cure: replace torque converter lockup solenoid

2. Transmission is stuck in high gear and did not automatically shift back down to 1st gear when you come to a stop. This would not buck like a bronco but takeoff will be very poor because the trans is stuck in high gear.
Try shifting into low and see if the problem is cleared. This was similar to yours also in that it took a while for it
to warm up enough to happen.
Cure: this was under warranty and they replaced the valve body.

No my check engine light is not on, nor has it ever come on while I am experiencing this problem. It only happens at speeds under 30 mph and is most noticeable when accelerating from a complete stop. It feels like I am dragging a large heavy object behind us and then once I get to 30 and above I dont seem to notice it. It is not bad, but am afraid it will get worse and need to know if its safe to drive. My old mechanic who moved to another state said to buy some fuel injection cleaner and dump it into my gas tank in case the fuel injectors are dirty. So I guess that is what I will try.

If it works fine at highway speeds and at full throttle it most likely is not a fuel delivery problem.

Try checking the computer for codes, even though the CEL never came on - light may not be working. If running this bad it seems surprising that it wluldn't have come on

Is it running rich, black or smelly exhaust when this is happening.

The coolant temperature sensor is a suspect also as well as a bad computer